The number one reason we recommend that our customers have furnace maintenance done at least once a year is for safety. This is the most important factor there is to using any major appliance, especially those are powered by natural gas.
Unfortunately, though the risks are not as high as they used to be, there is the possibility that carbon monoxide can leak into your home when you use your heater. This is particularly true if it’s not maintained properly. And you aren’t completely risk free if you use an electric-powered system either—electrical fires are a very real risk.